Rubber hardness-mixing?

[orion1]

Hello,
We have problem with rubber hardness it is sometimes higher and sometimes lower with same raw materials, so could somebody tell me how can we encrease hardness during mixing step in our production. Does the odrder of adding raw matterials has some infulance of the hardness or temperature or something else. Of course I know that hardness is function of filler properties and quantity.
Thank you.

 

[EdStainless]

I have only made rubber compounds in a lab setting, but my experience is that the order of addition and rate of addition are both factors in the finished porperties. The real issue is probably related to the peak temp reached during mixing. If you see variations over weeks or months then things like changes in humidity could also have an effect. Some fillers like to absorb moisture.

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